What are the only magnetic compass correctors that correct for both permanent and induced effects of magnetism?

Correct Answer: Option B — Heeling magnets

The heeling magnet is unique because it corrects for both permanent magnetism (vertical component) and induced magnetism caused by the vessel's heel. As the ship rolls, the vertical magnetic field changes; the heeling magnet compensates for these dynamic effects, ensuring the compass remains stable during heavy weather and maneuvers.